This invention relates to a tunnel wall structure constructed by a shield process.
In the prior art constructing a tunnel wall structure by the shield process, reinforced concrete segments are assembled progressively using an erector with the progress of a shield machine. There have been proposed various means for joining the concrete segments at the time of the assembly. In one of these means, which is most extensively used in practice, joint members are burried end portions of adjacent concrete segments and clamped by bolts and nuts.
The wall structure that is obtained by assembling the concrete segments in the form of a ring is required that it can perfectly withstand the earth pressure as a whole. In additions the individual concrete segments in the ring-like wall assembly experience a bending moment, which is highest on the inner wall surface. Accordingly, the joints that connect adjacent concrete segments in the peripheral direction of the wall structure are required to have a high tensile strength.
Meanwhile, individual concrete segments have to be comparatively readily positioned in their width direction, i.e., in the direction of the tunnel, and the tunnel wall structure has to be constructed comparatively speedily .